from kivy.app import App
from kivy.uix.widget import Widget
from kivy.properties import ObjectProperty
from kivy.uix.label import Label
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.popup import Popup

class Widgets(Widget):
    def btn(self):  #trigger
        show_popup()

class P(FloatLayout):
    pass

class MYpopApp(App):
    def build(self):
        return Widgets()

def show_popup():
    show = P()

    popupwindow = Popup(title = "PopupWindow_Introduction", content = show, size_hint = (None,None), size = (400,400))

    popupwindow.open()

if __name__ == "__main__":
    MYpopApp().run()